Portable eye magnet



Aug. 6, 1957 R. c. PAPE ETAL 2,301,523

' PORTABLE EYE MAGNET Filed July 6, 1955 3 66 I l/Y/l I "ll Ill 1 FlG.l

FIG. 2-

INVENTORS: ROBERT (-3. PA'PE GEORGE M. WALLERICH ATT'Ys United States Patent PORTABLE. EYE MAGNET Robert C. Papa, Chicago, and George M. Wallerich,

Hinsdale, 11]., assignors to V. Mueller & Co., a corporation of Illinois Application July 6, 1955, SerialNo. 520,219

12 Claims. (Cl. 128--1 .4)

This invention relates to an eye magnet for use in hospital operating rooms to remove magnetic materials during operations, and more particularly to an electromagnetic eye magnet which is spark-proof and explosionproof.

Magnets of various types have been devised for the extraction ofi-ron filings or thelike from the eyeball and have generally been of two specific varieties. One of these varieties is in the permanent magnet and its use has been extremely limited due to the fact that the amount of magnetism generated is usually inadequate for the job.

The other variety, the electromagnet, has been more satisfactory since the strength of the magnet can be determined by the size of the core and the number of field windings, but here too the use has been limited by the fact that the Wiring and connections are liable to produce sparks which may cause a minor explosion in the area of the operation, particularly where oxygen in concentrated form. is used and where explosive gases for anesthesia may be employed.

The major problem presented by the electromagnetic variety of eye magnet is that the thermostatic controls have generally been fuses or circuit breakers of the ordinary variety and arrangement and these devices have been exposed to the air while in heat-exchange relation with the core of the magnet so that upon breaking of the circuit, a spark is almost inevitable. Also thermostatic control arrangements heretofore attempted have been inadequate to properly prevent overheating of the instrument because sufficient proximity to the point of normal heat concentration could not be obtained.

It is the object of the present invention to overcome the aforementioned difficulties or weakness of the magnetic force on the one hand and combustion hazard on the otherby provision of an electromagnetic eye magnet which has the fuse or thermostatic control. means completely sealed off from contact with the. surrounding atmosphere while being disposed in good heatrexchange relation with the core ofthe magnet. a

Other objects of the invention are. to provide a fuse or thermostatic control, adapted to. prevent overheating of the c0re, Which is in anexceptionally good. heat-exchange relation to the core so that sensitivity of response and accurate timing of the circuit breaking action, is assured; to provide an electromagnet of the type indicated having an extremely compact and secure constructiomso that parts will not be dislodged by accidental movement or jarring of the magnet; to provide an electromagnet in which the wires are disposed in sealed-01f relation to the atmosphere at their terminals; and to provide a combination electromagnet and thermostatic control which is simple, and economical to manufacture and efficient in operation.

Referring to the drawings:

Fig. 1 is a side elevational view of an electromagnetic eye magnet according to the present invention;

Fig. 2 is a vertical sectional view of the eye magnet according to Fig. 1 disclosing the relationship of the fuse to the core of the magnet;

Fig. 3 is an exploded perspective view disclosing the internal structure of the thermostatic control and the means for securely locking the said control within the core of the magnet; and

Fig. 4 is a view taken on line 4-4 of Fig. 2 showing the terminal end of the internal connector for the ground and power input leads.

The electromagnet of the present invention provides the two particular advantages of an extremely good heatexchange relationship between the core of the magnet and the fuse or thermostatic control adapted to prevent overheating of the core, and an effectively sealed-off disposition of the fuse adapted to prevent accidental combustion and explosion, particularly under the delicate conditions encountered during an operation performed with the magnet.

Referring now to Fig. 1, the magnet 10 is provided at one end with a relatively blunt needle or probe portion 12 having an enlarged base portion 13 and an iron core adapted to be magnetically activated. Preferably the needle and its base are silver plated to resist external electrical influences and eliminate the possibility of sparks developing in this area through striking the needle against other metal objects. The needle 12 is preferably secured to an iron magnet core 14 in axial alignment by means of the stud 15 formed on the base 13 and threadedly re.- ceived in a recess 16 in the magnet core.

An electrical conduit 18 provides input leads 20 and 21 having connection through a connector block with internal, leads 20.1, 21.1 and 22 to form the magnetizing circuit for the magnet core, the lead 20.1 being suitably spliced to enameled copper winding wire wound around the core a predetermined number of turns to provide a coil 23 for producing the desired amount of magnetism in the core 14 and needle 12. Insulation and heat dissipation means for the. coil windings are provided by securing an aluminum spacer ring 24 on the core 14 a predetermined distance from the forward end thereof by suitable press-fitted splined or tongue and groove means or the like, and threadedly securing a hollow annular fuse holder body 26 to the other end of the core 14. Preferably an Allen-head set screw 28 is used to lock the body 26 to the core 14, which may be inserted or removed by means of an Allen wrench. An outer cover sleeve 30 of brass or aluminum is telescoped over the winding 23 and threadedly secured to the rear end of the fuse holder body 26, and a second relatively thick aluminum ring 32 is threaded into the sleeve 30 in abutting relation with the first ring 24. The ring 32 and the fuse holder body 26, which are relatively thick, effectively dissipate heat from the core 14 so that overheating will not be likely to: occur before use of the magnet has been completed.

ring 24 and fuse holder body 26, respectively. The outer wrapping 35 may be held in position by suitable tape, not shown.

The fuse holder body 26 is preferably threaded ex:

ternally at the end opposite the core 14 to engage" Wlthi the outer sleeve 30 as stated, and is internally threaded at the same end, as at 39, to engage a threaded nipple 40 projecting axially from the inner end of a connector block 41 which connects with the leads 2t and 21 from conductor cord 18. The cover sleeve 30 is also threaded externally at its rear end to have a cord connector housing sleeve 42 axially secured thereto.

As shown the connector block 41 has an enlarged body, rearward of the nipple 4t), and forms therewith a square shoulder which tightly abuts the end of the fuse holder body 26 when the parts are threaded together. Also the rear end of the block 41 has axially projecting, angularly spaced partition fins 44, as shown in Fig. 4, which provide three separated channels 45 for the reception of lead connectors 46 which in turn are suitably secured on axially projecting terminal pins 47 mounted in bores 48 extending axially through the connector block from end to end. The terminal pins 47 are disposed in a gas tight relation with the walls of the bores 48 and, as will be understood, the inner ends of the pins are arranged for soldered connection to the inner leads 20.1 and 21.1 which connect with the coil 23.

As shown in Figs. 2 and 4, the connector block 41 is made for connection with three Wires from the conductor 18, the third Wire 49 being a ground connection for the body of the instrument. This grounding of the instrument is obtained by providing a Phosphor bronze spring clip 50, suitably attached to the third terminal pin, which extends through a channel 51 in the outer wall of the connector body to resiliently engage the inner Wall of the housing sleeve 42 as shown in Fig. 2. Also, an axial bore 52 is provided in the connector block 4-1, near its periphery, for threaded reception of a lock screw 53 adapted to engage the rearward end of the fuse holder 26 and prevent relative turning of the parts 41 and 26 when the instrument is being assembled or disassembled.

The rearward or terminal end of the connector block 41 is enclosed by a cup-shaped sleeve 54 which fits over the partition fins 44 and has fitted engagement with the end margin of the block body. This sleeve terminates rearwardly in a tubular nipple-like portion having an inwardly tapered end opening adapted to provide a conical seat for the similarly tapered head 55 of a rubber conductor sleeve 56. The head 55 is larger than the sleeve 56 and also tapers rearwardly to meet the sleeve thereby providing a conical surface for sealing engagement with a similarly tapered inner end wall seat 57 at the rear end of the housing sleeve 42. As indicated in Fig. 2 the sleeve 56 extends rearwardly from the housing sleeve to provide a flexible sheath for protection of the conductor 18 at its entrance into the instrument body.

The connector block 41 and the sleeve 54 may be made of any suitable heat and impact resistant dielectric material, such as Bakelite. The housing sleeve 42 is preferably of cast aluminum.

The fuse holder body 26 has a longitudinal groove 60 formed therein between an aperture 62 extending partially around the body and the end of the body secured to the core 14, whereby the lead 20.1 may be introduced for winding on the core 14. Also the core 14 is preferably provided with a longitudinal groove 64 which terminates at a radial bore 66, spaced inwardly from the rear end, which bore in turn leads to. the axis of the core and opens into an axial recess 68 in the core. A thermally conductive, dielectric casing or housing 69 preferably of phenolic is adapted to fit in snug engagement in the recess 68 to hold a fuse or other circuitinterrupting means 70 in good heat-exchange relation with the core 14, and the continuation 22 from the coil 23 is thus lead through groove 64 and aperture 66 and thence through an end aperture 72 in the housing 69 in electrical connection with one end of fuse 70. The lead 21.1 passes from the connector block 41 through an aperture 74 in the housing 69 and into electrical connection 4 with the other end of the fuse 70 to form the circuit for magnetizing the core 14.

It will be appreciated that the fuse or other temperature responsive circuit-interrupting means could be disposed in a variety of positions along the core 14 without disturbing the desired heat-exchange relation, although for convenience of access and in view of the protection afforded by the construction described for the fuse-holder body 26, it is preferred to locate it at the rear end of the core.

The housing 69 has a tubular cup portion 76 and a cap 78 adapted to be fitted thereto by virtue of lugs 80 on the cap, axial grooves 82 in the cup for receiving the lugs, and'peripheral grooves 84 in the cup to retain the cap in locked position as in a bayonet-type of connection. A compression spring 86 is disposed at the bottom of the cup 76 and the ends of the leads 22 and 21.1 are each provided with metal contact discs 88 and 90 soldered thereto to be held against either end of the fuse 70 by means of the said spring 86, the spring normally bearing between the bottom of the cup and the disc 88 to urge the fuse toward the disc 90. With the foregoing arrangement the fuse 70 may be removed and replaced through the opening 62 in the holder body, the cap 78 being first removed by manual turning and withdrawing to permit the fuse to drop out of the housing 69 gravitationally. Insertion of a new fuse and replacement of the cap .78 automatically restores the winding circuit to operative condition. 7

In use, the magnet is connected to a foot switch and rectifier which are also suiably protected against excessive temperatures and against hazards of spark-induced combustion, the foot switch being connected in turn by a flexible cord to power supply lines. Since these features are not actually any part of the invention, they are not set forth in the drawings and are referred to herein only for the sake of completeness. The switch, for example, may be a push button station manufactured by The Square D Company for controlling heavy duty pilot loads of 600 volt maximum A. C. or D. C. The rectifier may be selenium, assembled with 16 plates which are three inch square and bridge connected. These parts are provided with suitable cover, connector and insulator elements to form a unit adapted for use with the eye magnet of the invention in locations where danger of explosions must be kept in an absolute minimum.

The magnet has been subjected to various tests by the Underwriters Laboratories, Inc. in order to determine the safety characteristics of the device. In a temperature test, for example, the magnet was started at room temperature and then operated continuously for 1% minutes while energized at volts A. C. The time of 1% minutes is the maximum recommended oeprating time, and thermocouples were located at critical points on the device such as the magnet coil tip, center, rear, and lead and the external body of the magnet during four tests. In no instance did the components tested exceed their respective permissible temperature rise lmits within any of the 1 /2 minute test periods.

The magnet was also subjected to a dielectric strength test potential of 1230 volts A. C. applied between the current carrying parts and the normally grounded parts for a one-minute period. The result of this test was that the test potential was maintained without breakdown.

In a fusible safety link test, thermocouples were placed on the magnet housing over the midpoint of the coil, using midget fuses rated 3.2 amp., volts. Five individual tests were conducted, the first test with four cycles of 1% minutes on and 1% minutes off and then keeping the magnet on continuously until the fusible safety link opened the circuit. The remaining four tests were conducted with the supply circuit continuously energizing the magnet. Throughout the tests, the enclosure was connected to ground through a three ampere fuse. In

no instance did the temperature'at any point exceed 180 C., the maximum temperature considered safe for such magnets in hazardous locations, and the fuse to ground remained intact.

The magnet was also subjected to drop tests, in which the magnet housing, with cord connectors attached as in use was dropped ten times for a distance of thirty-six inches onto a. concrete floor. No rupturing or distortion of joints occurred and the metalportions of the magnet did not cause sparking on contact with the concrete floor.

The Underwriters study concluded that the magnet satisfied the safety requirements for the conditions in which it would be used, and authorized listing of the device.

Accordingly, applicant has provided an electromagnet which assures accurate thermostatic control so that overheating will not develop, which is exceptionally strong and durable and which provides an explosion-proof housing for exposed parts such as the circuit breaker and windings, as well as a spark-proof operating portion or needle so that the device is entirely satisfactory for use in the hazardous conditions of an operating room.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claims:

We claim:

1. An electromagnetic eye magnet comprising an elongated cylindrical metallic core, an electric winding for magnetizing said core, a thermostatic circuit interrupter electrically in series with said winding, a housing for said circuit interrupter formed within said core axially thereof whereby said interrupter is in good heat-exchange relation with said core to afford temperature control for said magnet, means surrounding said core for sealing said interrupter from atmosphere, and a needle element at one end of said core adapted to be magnetically energized on magnetization of said core.

2. The construction according to claim 1, wherein the said core is provided with a recess disposed axially at one end, and a heat conductive dielectric casing for said circuit interrupter snugly received within said recess, said casing being adapted to receive conductor leads thereinto for series connection of said circuit interrupter and said winding with a power source.

3. An electromagnetic eye magnet comprising an elongated cylindrical metallic core, a winding surrounding said core for magnetizing said core, a temperature responsive circuit interrupter connected in series with said wind ing, a housing for said interrupter formed internally of said core, and a housing for said winding comprising a heat conductive spacer ring mounted on one end of said core adjacent one end of said winding, a hollow heat conductive body mounted on the other end of said core adjacent the other end of said winding, an insulating material covering said winding between said ring and body, and an elongated cylindrical cover sleeve mounted on and extending between said ring and body and enclosing said winding and the insulating material thereon, said core having a needle extending from said one end and adapted to be magnetized upon magnetization of said core.

4. In the construction according to claim 3, a relatively thick aluminum ring secured on said one end of said core in internal surface engagement with said cover sleeve and in abutting relation to said spacer ring adjacent said needle, whereby to dissipate heat away from said needle.

5. The construction according to claim 3, wherein said core is formed of iron and said needle is formed of iron and threadedly received in said core in axial alignment therewith, said needle having a relatively soft magnetically permeable coating whereby to render it substantially spark-proof.

6. An electromagnetic eye magnet comprising a cylindricalcore, a winding for said core, a circuit interrupter in series with said winding, a thermally conductive dielectric casing for said interrupter, an axial bore at one end of said core adapted to receive said casing therein in relatively snug engagement therewith, said casing having a removable cap portion extending beyond said core, a hollow cylindrical heat conducting body secured to said core over said cap, a heat conducting ring of the same diameter as said body secured adjacent the other end of said core, a cover sleeve fitted upon and extending between said ring and said body to enclose said winding, and a relatively blunt needle secured to the said other end of said core and projecting therefrom, said needle being formed of a magnetically permeable metal having a silver coating.

7. An electromagnetic eye magnet comprising a cylindrical core, a winding on said core, a fuse connected in series with said winding, a thermally conductive dielectric housing for said fuse, said core having a cylindrical recess disposed axially therein for receiving said housing and fuse in relatively snug engagement therewith, said core having a passage leading from its outer surface to said recess whereby one end of said winding may be led into connected relation with one end of said fuse, and a pair of power supply leads having connection. with the other.

end of said winding and the other end of said fuse respectively.

8. The construction according to claim 7, wherein said fuse housing comprises a cylindrical cup member and a cap member removably secured thereto, said cup member and cap member having axial apertures 'therethrough to receive said Winding lead and one of said supply leads respectively, said cup member having a spring element therein adapted to bias said fuse toward said cap when said housing is in assembled condition, and said leads being provided with conductive discs at the ends adjacent said fuse for eifecting'electrical connection between said fuse and said leads.

9. In the device according to claim 7, a hollow cylindrical body secured to one end of said core, said fuse housing extending at least to the end of the core to which said body is secured, a heat conductive ring mounted on said core adjacent the other end thereof, said body and ring having substantially the same diameter, a cover sleeve fitted to and extending between said ring and body in overlying relation to said winding, and a relatively blunt needle of magnetically permeable metal secured axially to said core at said other end thereof.

10. The construction according to claim 9, wherein said hollow cylindrical body is threaded externally on the end opposite the end secured to said core to threadedly engage with said cover sleeve, said cover sleeve being threaded externally and having a hollow cord connector housing sleeve in threaded axial relation therewith, said body having an internally threaded axial opening in the end opposite said core and a connector block threadedly secured therein within said connector housing sleeve, said connector block being of relatively reduced diameter at its connection with said body and having a portion of relatively large diameter extending axially therefrom, a plurality of terminal means on the outer end of said connector block having conductors extending axially into the portion of reduced diameter for connection with said leads, means for locking said connector block against rotation relative to said body, and means Within said connector housing sleeve and bearing axially between the outer end of said housing sleeve and large end of said connector block whereby to enclose said terminal means and maintain the same in sealed-0E relation to the interior of said housing sleeve.

11. The construction according to claim 9, wherein said core is formed of iron having a threaded axial recess at the end adjacent said ring, and wherein said needle is formed of iron and is threadedly received in said recess,

, 7 said needle'having a silver coating thereon to maintain said needle in substantially spark-proof condition.

12. The construction according to claim 9, wherein said cylindrical body is provided with a central aperture extending partially therearound and a longitudinal groove in its outer wall extending between said aperture and the end of said body secured to said core, and wherein said core is provided with an external longitudinal groove leading into the passage in said core opening into said recess for said fuse, whereby one of said power supply leads may be introduced through said cylindrical body for connection with said winding and whereby said winding may be led by said core groove and passage to said recess and into electrically connected relation with said fuse.

References Cited in the file of this patent UNITED STATES PATENTS 2,436,538 Wing Feb. 24, 1948 

